Gas pressure is a measure of the mechanical interaction of gas molecules with the surface of an object placed in that gas. Gas pressure is proportional to molecular concentration and gas temperature.
Methods for measuring gas pressure, based on characterizing a mechanical membrane deformation caused by the pressure differential on both sides of the membrane, are well known in the art. These methods can be used to measure both absolute and differential pressure. When the absolute pressure is of interest, one has to build a structure with a known pressure maintained on one side of the membrane, with the mechanical properties of the membrane being precisely designed for a given pressure range. This makes sensor construction complicated and susceptible to damage when the sensor is subjected to pressures outside the intended measurement range.
Vacuum measurement methods based on finding particle concentrations, such as the thermocouple gauge and the ion gauge methods, are also well known in the art. However, both the thermocouple gauge and the ion gauge methods suffer from disadvantages. The thermocouple gauge method is highly non-linear and has a limited dynamic range. The ion gauge method can generally only be used at high levels of vacuum and will generally be damaged if turned on at higher pressures. The ion gauge method also requires a high voltage electric source, which effectively prohibits its use in portable applications.
Also known is a method for measuring gas pressure by characterizing the damping effect of the gas on the motion of an oscillating structure excited by an external (i.e., other than by the gas itself) influence. However, sensors of this type have not seen widespread commercial application due to difficulties in building the mechanical structures and the electronic transducers necessary to achieve the required accuracy, dynamic range, response time and durability.
As a result, one object of the present invention is to provide an improved pressure sensor.
And another object of the present invention is to provide an improved method for measuring pressure.